新生儿喉罩插入满意时七氟醚吸入的半数肺泡气浓度

Minimum alveolar concentration of sevoflurane for insertion of laryngeal mask airway in neonates

目的探讨新生儿喉罩插入满意时七氟醚吸入的半数肺泡气浓度（MACLMA）。方法全麻下行择期手术新生儿30例，年龄1～28d。吸入8％七氟醚高浓度诱导，患儿体动消失后调整吸入七氟醚的浓度以达到呼气末浓度的预设值，维持该预设值3min后插入喉罩。七氟醚预设浓度根据序贯法，首轮初次预设浓度为3．3％，相邻浓度梯度比为1．1（试验进程是将剂量按等比级数排列，以便有等间隔的对数剂量）。插入喉罩即刻以及其后的1min内患儿出现呛咳、肢体运动、无法插入喉罩、屏气、喉痉挛或低氧血症中的任意一项即认为插入喉罩不满意，下一例升高一级浓度；若喉罩插入满意，下一例降低一级浓度。计算MAQva和95％可信区间（CI）。结果新生儿七氟醚MACLMA为2．34％（95％CI2．14％～2．55％）。13例患儿插入喉罩发生呛咳、体动，但均未发生喉痉挛、低氧血症等不良反应。结论新生儿喉罩插入满意时的七氟醚MACLMA2．34％（95％CI2．14％～2．55％）。

Objective To investigate the minimum alveolar concentration of sevoflurane for insertion of laryngeal mask airway（MACLMA） in anesthetized neonates. Methods Thirty neonates, aged 1-28 days, with an ASA physical status Ⅰ or Ⅱ, underwent elective surgery under general anesthesia induced by inhalation of 80% sevoflurane in oxygen. After loss of body movement, the designated endtidal concentration of sevoflurane remained stable for at last 3 min, and then LMA was inserted. Each target concentration at the time of insertion was predetermined by the Dixon up-and-down method （with adjacent concentration ratio 1.1 as a step size）starting at 3.3% end-tidal concentration of sevoflurane. Successful insertion was defined as excellent inserting condition（no cough no movement of the limbs,no breath holding,and no laryngospasm）. Results The mean MACLMA of sevoflurane to achieve successful LMA insertion in 50% of neonates was 2.34%, and 95% CI was 2.14%-2.55%. Conclusion LMA insertion can be safely accomplished without coughing,moving,or any other airway complications in 50% and 95% CI of neonates at 2.34% and 2.14%-2.55% end-tidal concentration of sevoflurane.